1. Technical Field
The present invention relates to a blood coagulation analyzer, a blood coagulation analysis method, and a computer program product.
2. Background Art
Conventionally, there has been known a blood coagulation analyzer that optically measures a blood sample to analyze, based on the measurement result, the clotting function of the blood sample (for example, see Japanese Unexamined Patent Publication No. 58555/1985 and Japanese Unexamined Patent Publication No. 123140/1998).
According to the blood coagulation analyzers disclosed in Japanese Unexamined Patent Publication No. 58555/1985 and Japanese Unexamined Patent Publication No. 123140/1998, light is emitted to a measurement sample prepared from a blood sample and a clotting reagent (a prothrombin time (hereinafter also referred to as “PT”) measurement reagent, a partial thromboplastin time (hereinafter also referred to as “PTT”) measurement reagent, and an activated partial thromboplastin time (hereinafter also referred to as “APTT”) measurement reagent). Then, the temporal change of the scattered light from the measurement sample is measured to thereby perform a PT measurement, a PTT measurement, or an APTT measurement.
Japanese Unexamined Patent Publication No. 58555/1985 also discloses that a blood coagulation analyzer is used to calculate a value corresponding to the fibrinogen concentration in the blood sample (hereinafter also referred to as derived fibrinogen concentration (dFbg value)), by multiplying, by a fixed coefficient, a scattered light change amount from the start of the clotting reaction to the end of the clotting reaction detected in a PT measurement or an APTT measurement for example.
It is noted that Japanese Unexamined Patent Publication No. 58555/1985 suggests that a dFbg value also can be calculated even when the temporal change of transmitted light from a measurement sample is measured and the change amount of the transmitted light from the start of the clotting reaction to the end of the clotting reaction is used.
A fibrinogen concentration is basically measured by an exclusive fibrinogen concentration measurement reagent. However, this measurement requires a lot of time and cost. To prevent this, it is very useful, as disclosed in Japanese Unexamined Patent Publication No. 58555/1985, to use the data detected in a PT measurement or an APTT measurement for example to calculate a dFbg value by computation so that the resultant value is used instead of the fibrinogen concentration.
However, when the dFbg value calculated by computation is an abnormal value deviating from a predetermined range, the dFbg value cannot be used instead of the fibrinogen concentration from the viewpoint of reliability.
On the other hand, even when the fibrinogen concentration is measured by an exclusive fibrinogen concentration measurement reagent, if the measurement result is an abnormal value such as the one deviating from a predetermined range, it is required to prepare again another measurement sample having a different dilution magnification ratio to measure again the fibrinogen concentration. This has caused a disadvantage where the time and the cost required for the measurement are increased.
Furthermore, blood samples of some subjects may include a large amount of interfering substance such as chyle and bilirubin. Thus, when a blood sample including a large amount of interfering substance is measured, the interfering substance has an influence on the change amount of scattered light and the change amount of transmitted light from the start of the clotting reaction to the end of the clotting reaction. Thus, it has been difficult to accurately calculate a dFgb value.